Chromatography column

ABSTRACT

A chromatography column includes a tubular member with an inlet end and a slidable porous member that bounds a chromatography media. The porous member is spaced sufficiently from the inlet end to define a receiving region.

REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.09/137,278, filed Aug. 20, 1998, now U.S. Pat. No. 6,139,733, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The invention relates to introducing a sample into a chromatographycolumn.

Liquid chromatography is a technique for separating the individualcompounds that exist in a subject sample. In employing the technique,the subject sample is carried in a liquid, called a mobile phase. Themobile phase carrying the subject sample is caused to migrate through amedia, called a stationary phase. Different compounds will havediffering rates of migration through the media, which effects theseparation of the components in the subject sample. Liquidchromatography is commonly performed with reusable columns or withdisposable cartridges, both of which are usually cylindrical, in whichthe media bed is bounded axially by porous plates, or plates containingdefined flow paths, through which the mobile phase will flow. (See U.S.Pat. No. 4,250,035 to McDonald et al. and U.S. Pat. No. 5,601,708 toLeavesley)

When chemists optimize liquid chromatographic separations conditions,they may need to dissolve the sample mixture in a dissolution solventwhich may be nonideal for elution. This can result in poor separationand poor recovery of desired components.

One solution to this problem is to pre-absorb the sample onto a mediaprior to chromatography. This involves dissolving the sample mixture ina suitable solvent and adding an amount of a dry media (usually similarto the media being used for the separation) to this solution. Thedissolution solvent is then evaporated off, usually using a rotaryevaporator, leaving the sample mixture dry, and absorbed to the media.The pre-absorbed media is then placed at the head of a pre-packed glass,metal or plastic chromatography column, and the optimizedchromatographic solvent would flow through the pre-absorbed media andthen through the column of separation media. This method has thepotential hazard of the operator coming into contact with the drypowdery media both before and after the addition of the sample. Thismethod also can lead to poor separations and recovery.

SUMMARY OF THE INVENTION

In one aspect, the invention features, in general, a chromatographysample module including a flow-through member having an inlet and anoutlet and chromatography media within the flow-through member. A sampleis added to the media, and the module, with the sample carried therein,can then be connected to a separation column.

Preferably the chromatography sample module is a tubular member that issized to fit within the end of a chromatography column that is used forseparation of the sample contained on the media in the module.Alternatively, the module can be connected to the chromatographyseparation column by a flow line. The sample in the dissolution solventcan be added to the sample module, and then the dissolution solvent canbe evaporated. Alternatively, the sample in the dissolution solvent canbe added to the sample module as a liquid without evaporation.

In another aspect the invention features a rack of sample modulesarranged in an array.

Embodiments of the invention may include one or more of the followingadvantages. The samples can be easily introduced into separationcolumns. Various solvents can be used for separation and dissolution ofthe sample, permitting optimization of the separation procedure. Samplesare easily preprocessed, and the operator is not exposed to the mediabefore or after adding the sample. A large number of samples can beprepared for processing at one time, facilitating the carrying out ofmultiple separations at one time.

Other features and advantages of the invention will be apparent from thefollowing description of the preferred embodiments thereof and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a chromatography system according tothe invention.

FIG. 2 is a vertical sectional view of a chromatography sample moduleused in the FIG. 1 system.

FIG. 3 is a plan view of a rack containing a plurality of the FIG. 2sample modules in an array.

FIG. 4 is an elevation of the FIG. 3 rack and modules.

FIG. 5 is a vertical sectional view showing the FIG. 2 sample module inposition between a sealing head and a chromatography column used in theFIG. 1 system prior to assembly.

FIG. 6 is a vertical sectional view showing the FIG. 5 components in anassembled and sealed state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown chromatography system 10 whichincludes a source of solvent 12, pump 14, sample module 16, liquidchromatography column 18, and sample collection vessel 20. In thissystem, the sample to be analyzed is preabsorbed onto media in samplemodule 16 prior to pumping solvent into module 16 and intochromatography column 18 to perform the separation procedure.

Referring to FIG. 2, it is seen that sample module 16 includescylindrical plastic tube 22, porous plates 24, 26 (made of inert plasticporous frits), and chromatography media 28 (only partially shown in thefigures) between porous plates 24, 26.

As appears from FIGS. 5 and 6, sample module 16 is designed to fitwithin chromatography column 18 at the entrance thereof and to besealably connected to the sealing head. Tube 22 is designed to fitwithin column 18 with minimal space between the two; in particular,there is 0.000″ to 0.010″ of radial clearance.

Sample module 16 can be filled with media that is the same as or isdifferent from the media of chromatography column 18. The sample isdissolved in the required solvent and added to the top of sample module16, where it is drawn into the media by capillary action. Thisdissolution solvent is then removed by placing sample module 16 in avacuum chamber. Heat may also be applied.

After sample module 16 has dried, it can be placed directly insideseparation column 18 so that the lower porous plate 26 is an in intimatecontact with the surface of the separation media or with a porous platewithin the separation column on top of the separation media.

Alternatively, sample module 16 can be placed in a remote tube connectedby a solvent line. Alternatively, the sample can be dissolved in aseparation solvent or a weaker solvent), and added to module 16. The wetmodule can then be loaded into the column or into a remote tube.

Examples of the types of complex samples where this technique hasparticularly advantageous use include synthetic organic reactionmixtures and natural product extracts, (e.g., from fermentation brothsor plants). These samples often need to be dissolved in a solvent notcompatible with the optimized separation solvent. Solvents are organizedaccording to their “solvent strength,” where hexanes have a value closeto zero, and methanol has a value of 0.95. Optimized separation eluentsoften have a lower solvent strength; e.g., hexane:ethylacetate 1:1 has asolvent strength of 0.295. If the sample needs to be dissolved in astrong solvent such as methanol, there will be a solvent strengthdifference of 0.655 seen initially after loading the sample onto thecolumn, and this will impair the separation of the sample. If the sampledissolved in methanol is instead preadsorbed to the media in the samplemodule and dried, the sample will not face this impairment duringseparation.

Referring to FIGS. 3 and 4, sample modules 16 can be supplied in racks32, and a whole rack of sample modules 16 can be efficiently prepared atone time rather than one at a time.

FIGS. 5 and 6 show the placement of a module 16 in a column 18 and thesealing of the module 16 and column 18 to a sealing head used to deliversolvent. Sealing head 110 has first head piece 112, second head piece124, intermediate head piece 128, and first and second annularelastomeric sealing members 134, 136.

First head piece 112 has body 114 with longitudinal axis 116. First headpiece 112 has outwardly extending shoulder 118, and contact face 120.Part of contact face 120 has a slightly conical shape or otherconcavity. First head piece 112 defines flow path 122 along axis 116.

Body 114 of first head piece 112 fits slidably through central openingsin second head piece 124, intermediate head piece 128, and first andsecond elastomeric sealing members 134, 136.

Second head piece 124 has outwardly extending compression member 146.Intermediate head piece 128 has narrow portion 148 distal from secondhead piece 124.

First elastomeric sealing member 134 is adjacent to both shoulder 118and narrow portion 148 of intermediate head piece 128. Secondelastomeric sealing member 136 is adjacent to both intermediate headpiece 128 and second head piece 124.

The outer diameter of tube 22 of sample module 16 is sized so that tube22 fits into column 18. The inner diameter of tube 22 is sized so thatit may slidably receive shoulder 118, first elastomeric sealing member134, and narrow portion 148 of intermediate head piece 128.

Intermediate head piece 128, second elastomeric sealing member 136, andsecond head piece 124 are sized to fit slidably into column 18, havingchamfered edges 140, filled with chromatography separation media 142,which is bounded axially by porous plates 144.

Referring to FIG. 6 seals are formed with the apparatus by insertingsample module 16 into column 18 so that second porous plate 26 abutsfirst porous plate 144. Referring to FIG. 5, sealing head 110 is theninserted into column 18 and tube 22 of sample module 16, so thatshoulder 118, first elastomeric sealing member 134, and narrow portion148 are within tube 22, and contact face 120 abuts porous plate 24.Sealing head 110 extends far enough into column 18 so that secondelastomeric sealing member 136 opposes the inner surface of column 18.

Downward compressive force applied to outwardly extending compressionmember 146 causes second head piece 124 to slide relative to first headpiece 112 and transmits compressive force to second elastomeric sealingmember 136, intermediate head piece 128, first elastomeric sealingmember 134, shoulder 118, porous plate 24, sample module media 28,porous plate 26, porous plate 144, and separation media bed 142. Thecompressive force causes first and second elastomeric sealing members134, 136 to expand radially so that first elastomeric sealing member 134forms a seal with tube 22, and second elastomeric sealing member 136forms a seal with column 18.

The seals are released by relaxing or removing the downward force tosecond head piece 124, thereby reducing the compressive force on thecomponents of sealing head 110 and reducing the radial expansion ofelastomeric sealing members 134, 136.

Preferably, tube 22 and column 18 are made of high-density polyethylene.However, the columns may be constructed of other materials, includingglass or stainless steel. Preferably, elastomeric sealing members aremade of a fluorocarbon polymer, such as that sold under the trade nameCHEMRAZ.

Other embodiments of the invention are within the scope of the followingclaims.

What is claimed is:
 1. A chromatography column for accepting a samplemodule comprising: a tubular member having an inlet end, an outlet end,and an inner surface; first and second porous members disposed withinsaid tubular member; and a chromatography media disposed within saidtubular member and bounded by said first and second porous members;wherein said first porous member abuts said chromatography media andsaid first porous member is also in downwardly slidable contact withsaid inner surface of said tubular member and is spaced sufficientlyfrom said inlet end to define a module receiving region for receiving asample module entirely within said tubular member.
 2. The chromatographycolumn of claim 1, wherein said tubular member further comprises asealing region between said inlet end and said module receiving region,said sealing region being sufficiently long to receive a sealing headfor making a seal with said inner surface of said tubular member.
 3. Thechromatography column of claim 1 wherein said inner surface of saidtubular member is substantially cylindrical throughout said modulereceiving region.
 4. The chromatography column of claim 1 wherein saidtubular member comprises polyethylene.
 5. The chromatography column ofclaim 1 wherein said tubular member comprises stainless steel.
 6. Thechromatography column of claim 1 wherein said tubular member comprisesglass.
 7. A chromatography column for use with a sample modulecomprising: a tubular member having an inlet end, an inner surface, anda module receiving region, said module receiving region being bounded bysaid inlet end and by a porous member; a chromatography media insidesaid tubular member, said chromatography media being bounded by saidporous member; wherein said porous member abuts said chromatographymedia and said first porous member is also in downwardly slidablecontact with said inner surface of said tubular member and is spacedsufficiently from said inlet end so that said module receiving region isdeep enough to permit a sample module to be inserted completely intosaid receiving region.
 8. The chromatography column of claim 7, whereinsaid tubular member further comprises a sealing region between saidinlet end and said module receiving region, said sealing region beingsufficiently long to receive a sealing head for making a seal with saidinner surface of said tubular member.
 9. The chromatography column ofclaim 7 wherein said inner surface of said tubular member issubstantially cylindrical throughout said module receiving region. 10.The chromatography column of claim 7 wherein said tubular membercomprises polyethylene.
 11. The chromatography column of claim 7 whereinsaid tubular member comprises stainless steel.
 12. The chromatographycolumn of claim 7 wherein said tubular member comprises glass.
 13. Achromatography column for accepting a sample module comprising: atubular member having an inlet end, an outlet end, and an inner surfacesaid tubular member having a chamfered region near said inlet end; firstand second porous members disposed within said tubular member; and achromatography media disposed within said tubular member and betweensaid first and second porous members; wherein said first porous memberis slidably fitted within said tubular member and is spaced sufficientlyfrom said inlet end to define a module receiving region for receiving asample module entirely within said tubular member.
 14. Thechromatography column of claim 13, wherein said tubular member furthercomprises a sealing region between said inlet end and said modulereceiving region, said sealing region being sufficiently long to receivea sealing head for making a seal with said inner surface of said tubularmember.
 15. The chromatography column of claim 14 wherein said innersurface of said tubular member is substantially cylindrical throughoutsaid module receiving region.
 16. The chromatography column of claim 13wherein said tubular member comprises polyethylene.
 17. Thechromatography column of claim 13 wherein said tubular member comprisesstainless steel.
 18. The chromatography column of claim 13 wherein saidtubular member comprises glass.